2,149 research outputs found
Space-Time and Matter in IIB Matrix Model - gauge symmetry and diffeomorphism -
We pursue the study of the type IIB matrix model as a constructive definition
of superstring. In this paper, we justify the interpretation of space-time as
distribution of eigenvalues of the matrices by showing that some low energy
excitations indeed propagate in it. In particular, we show that if the
distribution consists of small clusters of size , low energy theory acquires
local SU(n) gauge symmetry and a plaquette action for the associated gauge
boson is induced, in addition to a gauge invariant kinetic term for a massless
fermion in the adjoint representation of the SU(n). We finally argue a possible
identification of the diffeomorphism symmetry with permutation group acting on
the set of eigenvalues, and show that the general covariance is realized in the
low energy effective theory even though we do not have a manifest general
covariance in the IIB matrix model action.Comment: 25 page
Removing black-hole singularities with nonlinear electrodynamics
We propose a way to remove black hole singularities by using a particular
nonlinear electrodynamics Lagrangian that has been recently used in various
astrophysics and cosmological frameworks. In particular, we adapt the
cosmological analysis discussed in a previous work to the black hole physics.
Such analysis will be improved by applying the Oppenheimer-Volkoff equation to
the black hole case. At the end, fixed the radius of the star, the final
density depends only on the introduced quintessential density term
and on the mass.Comment: In this last updated version we correct two typos which were present
in Eqs. (21) and (22) in the version of this letter which has been published
in Mod. Phys. Lett. A 25, 2423-2429 (2010). In the present version, both of
Eqs. (21) and (22) are dimensionally and analytically correc
Hamiltonian Formulation of Two Body Problem in Wheeler-Feynman electrodynamics
A Hamiltonian formulation for the classical problem of electromagnetic
interaction of two charged relativistic particles is found.Comment: 22 pages, 8 Uuencoded Postscript figure
Adaptive multi-agent system for a washing machine production line
This paper describes the implementation of a multi-agent system in a real industrial washing machine production line aiming to integrate process and quality control, allowing the establishment of feedback control loops to support adaptation facing condition changes. For this purpose, the agent-based solution was implemented using the JADE framework, being the shared knowledge structured using a proper ontology, edited and validated in Protégé and posteriorly integrated in the multi-agent system. The solution was intensively tested using historical real production data and it is now being installed in the real production line. The preliminary results confirm the initial expectations in terms of improvement of process performance and product quality
Anisotropic Null String Cosmologies
We study string propagation in an anisotropic, cosmological background. We
solve the equations of motion and the constraints by performing a perturbative
expansion of the string coordinates in powers of c^2, the world-sheet speed of
light. To zeroth order the string is approximated by a tensionless string
(since c is proportional to the string tension T). We obtain exact, analytical
expressions for the zeroth and the first order solutions and we discuss some
cosmological implications.Comment: 9 pages, plain Te
Multi-agent systems in industry: current trends & future challenges
This paper introduces the multi-agent systems paradigm and presents some industrial applications of this AI approach, namely in manufacturing, handling and logistics domains. The road-blockers for the current weak adoption of this technology in industry are also discussed, and finally the current trends and several future challenges are pointed out to increase the wider dissemination and acceptance of the multi-agent technology in industry
A variable star survey of the open cluster M37
A CCD photometric study of the dense galactic open cluster M37 is presented
and discussed. The majority of the analysed data are time-series measurements
obtained through an R_C filter. The observations were carried out on seven
nights between December 1999 and February 2000, and have led to the discovery
of 7 new variable stars in the field. Three of them have been unambiguously
identified as W UMa-type eclipsing binaries, while two more are monoperiodic
pulsating stars, most probably high-amplitude delta Scuti-type variables. The
remaining two stars seem to be long-period eclipsing binaries without firm
period determination. Johnson B and V frames have been used to construct a new
colour-magnitude (CM) diagram of the cluster, and to find the locations of the
new variable stars. The pulsating variables are most likely background objects.
The CM diagram is fitted with recent isochrones yielding the main parameters of
the cluster.Comment: 7 pages, 6 figures, accepted for publication in A&
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